The 27-year-old suspect in a deadly stabbing rampage last July at a facility for people with disabilities told police he sped up his plans for the attack after hearing he was being pursued by a gangster, investigative sources said Wednesday.

Satoshi Uematsu reportedly told police an acquaintance with underworld connections informed him on July 25 that he was being targeted by a gangster. The following day, he broke into the Tsukui Yamayuri En facility in Sagamihara, Kanagawa Prefecture, where he previously worked, and killed 19 residents.

It is unclear whether the suspect had in fact been pursued by a gangster. But prosecutors have decided in a psychiatric test that Uematsu is mentally competent to stand trial and plan to indict him on Friday, the deadline of his detention period.